Advantageously, the composition can be used as paint primer, finding highly diverse applications for which the drive is to provide coatings ensuring good protection against corrosion phenomena.
In this field, anticorrosive pigments, such as chromates, are currently used due to their effectiveness in protecting metal surfaces in the presence of water, of oxygen or of any other component liable to detrimentally affect metal surfaces, in organic formulations (paints).
The surfaces of interest are generally metal surfaces which it is desired to protect, in different types of industry, and can be of iron or of steel (coated or not coated with zinc or alloy based on zinc, aluminum, silicon, magnesium, and the like).
Nevertheless, chromates are harmful due to their high oxidizing power and must be replaced by other substances which are as effective but which are devoid of toxicity.
For substrates made of galvanized steel, alternative solutions to chromates have already been provided, such as, for example: calcium-exchanged silica pigments, pigments comprising zinc aluminum polyphosphates and/or magnesium aluminum polyphosphates and/or calcium aluminum polyphosphates and/or strontium aluminum polyphosphates, and the like.
In parallel with steels covered with zinc, there exist on the world market other types of steel coating based on zinc and on other elements, such as aluminum, silicon or magnesium, such as, for example, Galvalume® (Al: 55%, Zn: 43.5%, Si: 1.5%) or Galfan (Zn: 95%, Al: 5%).
Nevertheless, to address steels covered with Galvalume®, few specific solutions are currently provided for ensuring the replacement of chromates as anticorrosive pigments. Nevertheless, mention may be made of anticorrosive pigments which are devoid of toxicity, such as Novinox XCA02 (calcium-exchanged silica) or Novinox PAM (pigment comprising magnesium aluminum tripolyphosphate) of the Applicant, but which, in terms of anticorrosive performances, do not equal those of chromates.
This is why, in this context, the Applicant is providing a novel family of anticorrosive pigments which are particularly well-suited to the anticorrosive protection of steels covered with Galvalume® and which are also suitable for steels covered with zinc (galvanized steel, also known as HDG (hot dipped galvanized)).